Let-back mechanism for loom let-offs



-OFFs K. J. uNwlN LETBAGKMECHANISM FOR Loon LET Filed sept. 21, 1925 Feb. s, 1921.

Patente-d Feb. 8, i927..

KENNETH J'. UNWIN, 011V] ORCESTER, "MASSACHUSETTS, ASSIGNOB.

MASSACHUSETTS.

LET-BACK T/IECI-IANISM FOR LOOM LET-OFFS.

Application led. September 21, `1925. Serial No. 573469.y

This invention relates to let-ons for looms and more particularly to let-back mecha- `nisms'by means of which the warp and cloth may be moved rearwardly at the time of a pick out. It not infrequently happens that a mispick will not be detected until a number of picks Vafter it occurred and thev weaver is required to unweave back to the mispick to remove the latter. rIhis process is accomplished by taking out the picks laid subsequent to themispiclz, after which it is necessary to move the fell ofthe cloth back t0 the position the reed occupies when on front center. It isl desirable that in this reverse motionv the` yarn be placed under the same tension as existed before the pick outand it is further desirable that the friction devices which normally retard Vthe movement of the warp beam or drum be adjustable from the accordingly the principal object of my invention to provide an improved adjustment for friction let-offs accessible from the front of the loom and so arranged as to permit a reversal of the warp while keeping' the same underA the' same tension which exists under ordinary weaving conditions.

. It is astill' further object of my invention' to' [employ the usual type of adjustment rendering the same positive in both ydirections andmaking it possible to detach the same .from its normal position so` that the friction maybe temporarily increased or decreased at the will of the operator. y

tion to providea iiexible frictionband of fixed length `to cooperate with a two-part friction drum 'the position of which is varied by means of a wedge controlled from v the usual handle extending towardthe front of theloom. i With vthese andl other objects in view which will appear as the description proceeds, my invention resides in the combination and arrangement of parts hereinafter described and set forth in the claims.

, In the accompanying drawings wherein I lhave shown .a convenient embodiment of my invention,

Fig. 1 is a vertical longitudinal section through a loomhaving my invention ap-k plied thereto, Y v y Fig.l 2 is an enlarged vertical section on yline 2-'2 of Fig. `1,

front ofthe loom. It is Fig. 3 is a vertical section on line 3--3 of Fig. 2, .p

Fig. 4 is.afragmentary horizontal section on lin-e 1 -4; of Fig. 3,

Fig. 5 is a topjplan viewvof the wedge looking in the ydirection ofarrow 5, Fig. 2,

Fig. 6 is a section .on line 6-6 of Fig. 5 and y Fig. 7 is anenlarged vertical section on line 7-7 of Fig., 1. f

My invention is usable on various types of looms but is applicable `more, particularly to ducky looms where the warp may be derived either fromawarp beam mounted directly on the loom frame` or from a Creel disposed rearwardly ofthe loom and having associated therewith a warpdrum around which the warp threads extend when passing from the creel tothe `harness mechanism. I have chosen to illustrate my invention in connection with awarp delivery drum such as is used with creels but it is to be understood that I am not limited to this particular mode of employing my `in-, t

around which thewarpthreads W extend-k before ',passing yto the lharness mechanism not shown. kRigid with Asaid drum 11 is a gear 12 which meshes with a pinion 13 keyed to the hub 14: of bracketl which is loosely mounted on a shaft.16. It is a still further object of my inven- Said bracket is provided with a pair of arms 17 and 18, respectively, see Fig. 3, to which are secured the ends of a flexible frictionband 19 by means of bolts `2O. The band 19 isthus required to movewith the pinion 13 and the warp drum 11. An expansible drum engages the interior of the friction band 19 and is formed of two ypivotally connected parts 21 and 22, respectively, the latter partrbeing provided with ears 23 between which extends a pin 24. A lever 25y is loosely mounted on they pin `between the ears' and has an arm 26which is pressed against the' drum section 21. The degree of friction existing between the drum sections and the flexible band 19vis determined bythe position of the lever 25.

In order to move saidlever 25 angularly about the pivot thereof I provide a collar 27 loosely mounted on the shaft 16 and` y having. a slahbcd hub .28. The outer end ofthe shaft 16 is supported by .a bearing 29 and in order to vary the longitudinal ponsitionfof collar2 I provide a .forked wedge i30` Ibetween .said collar or from the lever25 to affect the position thereof. f

Said wedge ,is secured to rod 31 which is adjustably connected .at the .forward end .thereoftoa hand lever 32nivoted asat to 'theloomgframe The forward end of the lel verihas aportion extendinsr'between the undefined by said arms. y.able Vin 'hearings 88 formed on a bracket 39 per 'and lower ai'ms 34 and respectively, .of a .threaded block.

36 .mounted on a .screw 37 and can be exed into and out of the notch -Said screw is rotatseoured vto the loom frame and is held against .,'longitudinalmotion by a hand -wheel 40 on the upper sideof vthev upper bearing 38 and a collar y41 fixed to the screw of the under 4side ofthe upper bearing. The rear face of the blockfSG-engages the adi acent wall of the bracket and is therebvheld against rotationl as the screw :is turned. 4The matter thus far described Yrelates to the mechanism yfor adjustingtthe friction'between the han d 19 and the kdrum sections 21 and 22.

v aifordsmeans for turning the shaft 44.

As `previously stated it is desirable to re-A verse the direction of the warn drum and .this isaccomplished by mechanism controllable from the front of the loom. Said mechanism comprises a .worm gear 42 keyed to ther-shaft ldand meshing with the worm V43 fastened to the rear end -of an inclined r shaft 44 which is received lov bearings 45 se- At` hand wheel 46 This mechanism rprovides a readv means for reversing the warpl drum 11 through the fric- C on devices previouslv described. Resilient means 47 areconnected to the drum sections cured to the loom frame.

21 and 22 to (move the same together when y Voted together as at 48 f iA .the 1Vlever 25 is moved to relieve the friction. fUnder normal conditions the drum y11 will 1 .rotate and cause the flexible band. 19 to move `around the friction surface of the drum sections 21 and 22. Said drum sections are pivand the section 22 is keyed to the `shaft 1.6.as at 49. Inasmuch as .,wormgear 42 is heldA againstangular motion by worm 43 and is keyed to shaft 16, the

. sections 21 and 22 will also be ,held against enl l the' proper I'la-r A2,7 .toward :or fromthe lever V25 accordrotation 'as the` leather band 19 moves with 'the :warp drum 11. y f Aitbe desired to adjust the 4friction the screw 37 may be rotated in direction -either to move the coling :to whether the yfriction isto be increased `or decreased. 'v

At 'the time of pick out 'whenV the picks which were laid after the mispiclroccurred have vbeen removed, the hand wheel 46 isv turned to .give a reverse movementwtto -the drum sections 21 and 22 lthrouglirthe worm 43 and gear 42. This will cause tlieflexible band 19 yto move witli said sections and will in turn Vrotate the :pinion 13, gear 12 and warp drum 11. After the fell of the cloth has reached the reed when the ylatter is on r front center the hand wheel can .be rotated a little farther to cause slipping between the drum sections 21 and22 andthe Aflexible band 19, this latter procedure insuring that the warp and cloth are under the same tension which existed 'before .the pick out.

lTrom the foregoingit will be seen that the front of theloom for controllin'gt'he .friction and that the latter canhe reversed. to

`wish to be limited to the details `=herein'disclosed but what I claim is:

1. In a let-olf mechanism for looms fhaving a warp delivery means and affrict'ion surface movable therewith, an expansible friction element to cooperate with-'the 'friction means to' retard movement of fthe' -warp ldeliveryl means, a rotatable screw atffthe front of the loom, a ywedge to control thelexpansihle element, and yconnections from Ithe screw to the wedge to -move the Vlatter positively inopposite directions.

2. 1n a let-off mechanism for looms having a warp delivery vmea-ns and la .friction surface movable therewith, 'an expansible friction element cooperating with `the 4friction surface to retard movement-'of the'warp delivery means, means to expand the element, including a lever in'.v 'contact with a portion thereof and a wedge to positionthe lever, and means to move the wedge positively in opposite. directions and hold the same in any position thereof.

3. In a let-olf mechanism for v-looms having a warp delivery ineansand a friction .surface .movable therewith', an expansible friction element cooperating with'the friction surface to retard movement ofthewarp- 'l have provided a let-bach mechanism for vloom let-offs having a wedge-actuablefrom lever, and means to move the wedge positively in opposite directions and hold the same in any position cluding a screw mounted for rotation near the front of the loom.

4. In a let-oil' mechanism for looms having a warp delivery means and a `friction surface movable therewith, friction element cooperating with the friction surface to retard movement of the warp delivery `means, a lever to expand the element, a wedge to move the lever, a lever to position the wedge, a screw mounted at the front ci the loom for rotation, and positive connections between the screw and the second named lever to move the latter and the wedge in two directions by rotating the screw.

5. In a let-oli" mechanism for looms hav- 20 ing a warp delivery means and a friction thereof, said means in-y an expansible y surface `movable therewith, an expansible `friction element to cooperate with thev friction surface to retard movement of the warp delivery means, a wedge movable iny opposite directions, connections between the wedge and the element to vary the degree of expansion o said element, a lever to p0- sition the wedge having an arm capable of being flexed laterally, a screw mounted for rotation at the front of the loom@ block mounted on the screw and movable therealong by rotation -of thescrew, and a pair of spaced ears on said block between which the arm of the lever is lnormally positioned, the said arm being movable laterally out of alignment with the ears to position the wedge independently of the screw.

In testimony whereof I have affixed my signature.

KENNETH J. UNWIN.

hereunto 

